Flow Control

To make our programs dynamic and capable of making decisions, we use control flow structures: conditional statements and loops.

Conditionals: if, else if, and else

The if statement executes a block of code only if a specific boolean condition is true.

int temperature = 25;

if (temperature > 30) {
    System.out.println("Fa molto caldo!");
} else if (temperature >= 20) {
    System.out.println("Il clima è piacevole.");
} else {
    System.out.println("Fa freddo.");
}

Logical Operators

We can combine multiple conditions using logical operators:

• && (AND): Returns true if both conditions are true.
• || (OR): Returns true if at least one of the conditions is true.
• ! (NOT): Reverses the logical value of the condition.

boolean hasLicense = true;
boolean hasCar = false;

if (hasLicense && hasCar) {
    System.out.println("Puoi guidare.");
}

Loops: while and for

Loops allow us to repeatedly execute a block of code.

The while Loop

Executes the code as long as the specified condition remains true.

int count = 1;
while (count <= 3) {
    System.out.println("Conteggio: " + count);
    count++; // Increment count by 1
}

The for Loop

Ideal when we know in advance the number of iterations to perform. The syntax requires initialization, a termination condition, and an increment expression.

for (int i = 0; i < 5; i++) {
    System.out.println("Iteration: " + i);
}

Advanced Conditionals: the switch

When we need to compare a single variable against multiple constant values, the switch statement makes the code much cleaner than multiple chained if-else blocks.

int dayOfWeek = 3;
switch (dayOfWeek) {
    case 1:
        System.out.println("Monday");
        break;
    case 2:
        System.out.println("Tuesday");
        break;
    case 3:
        System.out.println("Wednesday");
        break;
    default:
        System.out.println("Other day");
}

Loop Control: break and continue

We can alter the normal flow of a loop using two special statements:

• break: immediately terminates execution of the innermost loop, exiting it completely.
• continue: skips the rest of the code in the current iteration and jumps directly to evaluating the condition for the next iteration (or the increment expression in a for loop).

for (int i = 1; i <= 5; i++) {
    if (i == 3) {
        continue; // Skips printing for the number 3
    }
    System.out.println(i);
}

Try it yourself